The present invention relates to distance measuring tools, and more particularly to rulers.
Tape measures, rulers of varying lengths (e.g., twelve inch rulers and yardsticks), folding (zig-zag) rulers, and more recently electronic devices (using, e.g., lasers) are all tools which are well known in the art for measuring distances. While each such tool can be used for that function, each also has their advantages and drawbacks for different uses.
Thus, electronic devices may be used in many applications and, depending on the device, may be used to measure short distances and/or long distances. For example, many land surveyors use laser measuring devices in their work. Of course, such devices are generally expensive and relatively complicated to use and thus are not appropriate for many users.
Tape measures may more easily be used to measure a variety of distances, including relatively long distances of hundreds of feet. Further, such tape measures may also be flexible enough to allow use in measuring other than straight line distances. However, the flexibility of tape measures is a disadvantage in measuring short distances, where rigid rulers are more convenient and less costly.
Such rigid rulers have a wide variety of uses, including not only measuring relatively small straight distances (e.g., up to twelve inches) but also functioning as straight edges for use in drawing straight lines. Further, such rulers have been widely used to teach various physical and mathematical concepts to school children. As a result, such rulers are not only something which can be used in schools, but are something which most schools typically require that a student include among his or her supplies. Therefore, it should be recognized that such rulers are often used by inexperienced and, in many cases, not yet fully coordinated children. Thus, they may not be readily used to measure anything other than straight lines. Further, their length may make it difficult for a person to carry (e.g., twelve inch rulers are typically too long to carry in a pocket, and even shorter rulers which may fit in an owner's pocket when walking may be broken or jab the owner when they sit down with it in their pocket). Zig-zag rulers, such as shown in U.S. Pat. No. 4,426,790, have been used to permit rigid rulers to be used to measure distances longer than the length of the ruler when folded. However, such zig-zag rulers are also relatively difficult to use, especially for school children, are not readily usable to measure anything other than straight lines, and due to the planar offset of each leg of the zig-zag ruler cannot be readily used as a straight edge and may somewhat distort the measurements taken (since the planar offset, which is slightly greater than the thickness of each leg, may either require that the legs be tilted slightly along the direction of measurement or may prevent the legs at each end of the distance being measured from being disposed directly against the object to allow for most accurate reading).
Other folding measuring devices are shown in, e.g., U.S. Pat. Nos. D-387,689 and 3,934,351. However, such devices have various drawbacks, such as susceptibility toward breaking after repeated bending, cost (of materials and/or manufacture, and/or the inability to be compactly stored when not in use.
The present invention is directed toward overcoming one or more of the problems set forth above.